For some time it has been a critical requirement for both soldiers and for those operating in extreme temperature environments, especially in the Arctic and in the desert, that a garment be provided which is both air and vapor permeable while at the same time having synthetic tubing carrying cooling or heating fluids in which close body contact is made with the tubing.
Typically, a heating/cooling garment, such as a vest, is made in which tubing is attached to a liner, with the liner then attached to fabric which forms the outer portion of the garment. While a wide variety of such garments exist, garments for this purpose are desirably stretchable and flexible to conform to the body of the individual, not only to provide mobility for arms and legs, but also to hold the cooling tubes closer to the body for more efficient heat transfer to the heating or cooling fluid. Additionally, flexibility produces less damage to the tubing during the flexure of the garment, with the garment being less susceptible to being torn when the material is flexible. Moreover, there is a requirement for lightweight construction, launderability, and dry cleanability. Additionally, since pressures within the tubing can reach 100 psi, the mating of the tubing to its substrate must be fluid pressure insensitive.
In the past, such a garment has involved the sewing of tubing to a substrate or liner which is porous enough to provide both for internal vapors to escape as well as to provide for air permeability. However, a major problem with sewn tubing is a problem called needleholing, in which every inch of the tubing is sewn to the porous substrate. Not only is there a potential problem in terms of pinhole puncturing of the tubing during the sewing process, the threads themselves provide a major irritant when these tubes are pressed into contact with the body. Additionally, since a T-shirt made in this manner can take as long as one day to manufacture and another day to test, the sewing method is intolerably slow and expensive, with registration problems of the tubing with a predetermined pattern making automatic sewing all but impossible.
Another reason that stitching is avoided is in so-called chemical protective clothing. Here, stitching tubing to any substrate for use in this application will result in needle holes, the size of which will permit unwanted chemicals to transit from one side of the garment to the other. Sewn tubing type garments are exemplified by Exotemp Ltd. heat transfer garments.
In order to provide an alternative to the sewn-in tubing, heating/cooling garments have been made with a bladder sealed at its edges, with the cooling fluid being contained within the bladder. However, while bladder-type garments do in fact conduct heat away from the body or conduct heat to the body, due to the two-coated fabrics which are joined together by heat, the resulting garment is non-breathable, non-stretchable and non-flexible. Additionally, there is a flexibility problem because of the large volume of liquid which is captured in the garment. Also, there is only one method of removing heat, e.g., conduction, since a bladder-type garment poses an impermeable barrier against natural sweating. Such a cooling garment thus completely eliminates the possibility of evaporative or convective cooling. Further, the edges of the bladder can come apart when subjected to pressures higher than 30 psi. Bladder type garments are exemplified by COOLVEST Model 17 manufactured by ILC DOVER.
Bladder type garments aside, methods other than sewing have been used to attach tubing to a liner or substrate. One such method involves brushing or rolling adhesives onto liners.
While brushed on or rolled on adhesives have been used in an attempt to adhere tubing to liners, the result is that all lining porosity is destroyed when the adhesive is massively applied across the substrate.
There is also a technique for adhesively taping the tubing to a liner, with adhesive tape contacting the liner to either side of the tube along its length. This system is exceedingly difficult to implement due to the fact that when the tubing is formed around small radius corners, the overlying strip of tape has to be notched to go around the corners. Also, it will be appreciated that the tape retards stretchability and permeability, adds unwanted stiffness to the garment and does not result in secure fastening of the tubing to the liner.
In general, heating or cooling garments are exemplified by U.S. Pat. Nos. 3,451,812; 3,425,486; 3,419,702; 4,691,762; 4,718,429; and 4,998,415. Other types of systems for body heating and cooling are illustrated in U.S. Pat. Nos. 4,114,620 and 5,062,424.
None of the above patents describe the utilization of a substrate or liner which is both air permeable and vapor permeable to which tubing is attached using fusible fabrics.
In summary, it is important to provide a garment that does not restrict the evaporative process in that it does not restrict the natural evaporation process of the human body, thereby preventing heat stress. It is therefore important that the garment not trap vapor as is the case with both bladder-type garments and those garments which have an excessive amount of adhesive blocking the naturally occurring pores in the liner. While some of the sewn in tubing garments provide for many of the above features, needleholing due to stitching and exhorbitant amounts of time spent in making the garment, as well as testing it after manufacture, preclude large scale usage. The sewn method precludes use in chemical protective uniform applications. Also, the sewn tubing method can be uncomfortable to the wearer.